Cryotherapy is a medical procedure used to treat a number of different diseases. It is also used to treat benign and malignant lesions. Cryotherapy is used in many of the human organs including liver, kidney, uterus, heart, eyes, breast, lung, kidney, and prostate. With regard to the various procedures in which cryotherapy is used, treatment of prostate cancer is one of the most common. Accordingly, this example for treatment of prostate cancer is utilized herein to describe and illustrate the disadvantages associated with use of cryotherapy, as well as the advantages of the instant invention, but the invention should not be considered as limited to this example.
Prostate cancer is the most common cancer diagnosis in men (except skin cancer). It is the second-most common cause of cancer deaths in men over the age of 65 (lung cancer is the most common). Current methods to treat prostate cancer include prostatectomy (robotic), radiation therapy, cryotherapy, and watchful waiting. Robotic prostatectomy and radiation are very expensive and cost between $40,000 and $60,000. They can have significant morbidity. Cryotherapy is the least expensive treatment, even less than watchful waiting. Cure rates are equivalent to radiation and slightly less than surgery.
One major complication of cryotherapy is injury to adjacent normal tissues. For example, in cryosurgery of the prostate used for treating cancer, the most significant side effect is injury to the nerves needed for erectile function. This detrimental side effect is extremely common because injury to these nerves occurs in 80% to 90% of the procedures performed today. The reason why this injury is so common is because these nerves are in close proximity to the prostate. Therefore, these nerves are directly exposed to lethal levels of cold temperature during cryotherapy, resulting in sexual dysfunction. Currently there is no device/method that significantly reduces this side effect.
In the example of a treatment for prostate cancer, cryotherapy devices insert hollow needles through the perineum, i.e., the region between the genitals and the anus. Liquid nitrogen or liquid argon is injected through the needles and is used to freeze the prostate itself, thereby eradicating the prostate cancer. Those of skill in the art know how cryotherapy treatment on the prostate is performed and one excellent exemplary overview of this procedure is found on the Web at https://www.youtube.com/watch?v=-OnqA-mJDWg&app=desktop, titled “Overview of Prostate Cryotherapy” by Galil Medical. A needle guide template having a row-and-column array of needle guide bores is placed against the perineum with the patient in the lithotomy position. With ultrasound visualization, the surgeon inserts cryoablation needles though various bores in the array and into the prostate. Temperature probes can also be inserted through other bores to monitor temperature within the prostate or adjacent, such as at the rectal wall or at the sphincter. Urethral protection is provided with devices such as a urethral warming catheter. Cycles of freezing are applied to the prostate under visualization until treatment has finished. The needles and template are removed after treatment is completed. An example of such a needle guide template 100 is shown in FIG. 1.
Present devices used to treat prostate cancer with cryotherapy are often used in salvage procedures where cancer has recurred or where other procedures (such as external beam radiation therapy or high dose rate brachytherapy) have failed. Now, cryotherapy is being used to treat primary prostate cancer, in which the entire prostate is treated along with the cancer. This procedure has beneficial results because it prevents the cancer from reoccurring in another location subsequently. Another procedure is becoming popularized—focal cryotherapy of the prostate. In this procedure, only a quadrant or section of the prostate that contains the cancer is treated. Focal cryotherapy was developed to eliminate erectile function injuries to help preserve erectile function, but it has succeeded only in exchange for an increase in the possibility of cancer reoccurrence. Focal cryotherapy is reserved for a select group of patients whose probability of cancer reoccurrence in another section of the prostate is minimal.
As mentioned above, one major side effect of any cryotherapy to treat the prostate (hindering it from becoming more popular) is the relatively high incidence of erectile dysfunction from nerve damage. Yet, another complication of prostate cryotherapy is rectal injury, which can and does occur because the posterior prostate is in close proximity to the rectum, e.g., in the Denonvilliers Fascia. The anterior rectum is at risk for thermal injury when adequately low temperatures for cell death in the posterior prostate occur. This risk is especially an issue when treating a post-radiated prostate because that space has been reduced from scarring.
In summary, current cryotherapy devices are not equipped to prevent nerve damage in a patient, thereby increasing the risk of impotence.
There are other ways to treat prostate cancer, for example. Surgical removal of the prostate, radical prostatectomy, is one way. However, radical prostatectomy is only effective if the prostate cancer is organ-confined. Side effects of radical prostatectomy surgery include temporary or permanent urinary incontinence and impotence. In addition, even if the patient is not impotent, removal of the prostate will result in dry orgasms for the patient. Further, there is a danger that the surgeon could cut one or more of the nerves, resulting in erectile dysfunction.
Radiation therapy is another form of treatment for prostate cancer. Forms of radiation therapy include permanent seed implants, high dose rate temporary brachytherapy, and external beam radiation therapy. One form of radiation therapy is the use of permanent seed implants. When using permanent seed implants therapy, radioactive seeds are injected into the prostate gland. The seeds are comprised of radioactive material encased within a titanium shell. A major disadvantage of seed implant therapy is the fact that it is difficult to determine whether cancer has spread during the procedure. In addition, side effects include bowel and bladder issues.
High-dose-rate brachytherapy is another treatment type and uses catheters that are inserted into the prostate and the tumor with the use of a CAT scan to position the catheters. An insertion device pushes a radioactive iridium wire into the catheters one by one to treat the tumor. Although high-dose-rate brachytherapy is seen as an effective alternative to permanent seed implants, the equipment and training costs associated with the treatment are very high. In addition, there is a distinct possibility that the seeds migrate and, in doing so, ultimately deliver too much radiation, causing damage to non-cancerous tissues, or deliver too little radiation, thereby failing to give a lethal dose to the cancer.
A final treatment type is external beam radiation therapy, which is used typically in situations where cancer has spread and is not confined to the prostate. Typical side effects include bowel and bladder issues because the radiation affects healthy tissue.
Each of these forms of treatment has the ability to burn normal adjacent tissue in a random and uncontrollable way. While cryotherapy is growing in its use for many procedures, especially for treatment of prostate cancer, currently, there is no feasible way to prevent these types of injuries to adjacent nerves/normal tissue without compromising the cancer-removing operation. One attempt to do so was through use of helium-warming probes, but that attempt was unsuccessful for a variety of reasons.
Thus, a need exists to overcome the problems with the prior art systems, designs, and processes as discussed above.
Rapid transition polymers (RTP) are discussed herein and it is believed that a brief overview would be beneficial. RTP developed by Pluromed, Inc., are polymers that exist in a liquid state at low temperatures and at room temperature, but quickly transition to a gel at body temperature. This phase change is fully reversible by cooling. It is noted that the polymers cannot re-solidify once dissolved. Some RTP are able to be injected into a mammal. One RTP substance was developed as an endovascular occlusion gel for vascular surgery under Pluromed's trademark LeGoo® and is FDA approved. In such use, LeGoo® is a viscous liquid at room temperature and becomes a firm plug in the vessel in which it is injected at body temperature. Once used in such a vessel-occluding procedure, a cooling mechanism, such as sterile ice, is applied to the site of the gelled RTP or cold saline is injected intravascularly until blood flow in the occluded vessel is restored. This RTP polymer is also FDA approved for the use in endoscopic urologic surgery to prevent proximal stone migration under Pluromed's trademark BackStop®. In particular, injected BackStop® forms a plug in the ureter to prevent stone migration during lithotripsy. BackStop® is marketed by Boston Scientific.